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-rw-r--r--src/mesa/swrast/s_blend.c28
1 files changed, 9 insertions, 19 deletions
diff --git a/src/mesa/swrast/s_blend.c b/src/mesa/swrast/s_blend.c
index f37a44015f1..5fa76322dce 100644
--- a/src/mesa/swrast/s_blend.c
+++ b/src/mesa/swrast/s_blend.c
@@ -1,4 +1,4 @@
-/* $Id: s_blend.c,v 1.15 2002/04/02 16:16:45 brianp Exp $ */
+/* $Id: s_blend.c,v 1.16 2002/04/02 23:36:51 brianp Exp $ */
/*
* Mesa 3-D graphics library
@@ -138,33 +138,23 @@ blend_transparency( GLcontext *ctx, GLuint n, const GLubyte mask[],
GLint temp;
#define DIV255(X) (temp = (X), ((temp << 8) + temp + 256) >> 16)
#endif
-#if 0
- const GLint s = CHAN_MAX - t;
- const GLint r = DIV255(rgba[i][RCOMP] * t + dest[i][RCOMP] * s);
- const GLint g = DIV255(rgba[i][GCOMP] * t + dest[i][GCOMP] * s);
- const GLint b = DIV255(rgba[i][BCOMP] * t + dest[i][BCOMP] * s);
- const GLint a = DIV255(rgba[i][ACOMP] * t + dest[i][ACOMP] * s);
-#else
const GLint r = DIV255((rgba[i][RCOMP] - dest[i][RCOMP]) * t) + dest[i][RCOMP];
const GLint g = DIV255((rgba[i][GCOMP] - dest[i][GCOMP]) * t) + dest[i][GCOMP];
const GLint b = DIV255((rgba[i][BCOMP] - dest[i][BCOMP]) * t) + dest[i][BCOMP];
const GLint a = DIV255((rgba[i][ACOMP] - dest[i][ACOMP]) * t) + dest[i][ACOMP];
-#endif
#undef DIV255
#elif CHAN_BITS == 16
const GLfloat tt = (GLfloat) t / CHAN_MAXF;
- const GLfloat s = 1.0 - tt;
- const GLint r = (GLint) (rgba[i][RCOMP] * tt + dest[i][RCOMP] * s);
- const GLint g = (GLint) (rgba[i][GCOMP] * tt + dest[i][GCOMP] * s);
- const GLint b = (GLint) (rgba[i][BCOMP] * tt + dest[i][BCOMP] * s);
- const GLint a = (GLint) (rgba[i][ACOMP] * tt + dest[i][ACOMP] * s);
+ const GLint r = (GLint) ((rgba[i][RCOMP] - dest[i][RCOMP]) * tt + dest[i][RCOMP]);
+ const GLint g = (GLint) ((rgba[i][GCOMP] - dest[i][GCOMP]) * tt + dest[i][GCOMP]);
+ const GLint b = (GLint) ((rgba[i][BCOMP] - dest[i][BCOMP]) * tt + dest[i][BCOMP]);
+ const GLint a = (GLint) ((rgba[i][ACOMP] - dest[i][ACOMP]) * tt + dest[i][ACOMP]);
#else /* CHAN_BITS == 32 */
const GLfloat tt = (GLfloat) t / CHAN_MAXF;
- const GLfloat s = 1.0 - tt;
- const GLfloat r = rgba[i][RCOMP] * tt + dest[i][RCOMP] * s;
- const GLfloat g = rgba[i][GCOMP] * tt + dest[i][GCOMP] * s;
- const GLfloat b = rgba[i][BCOMP] * tt + dest[i][BCOMP] * s;
- const GLfloat a = rgba[i][ACOMP] * tt + dest[i][ACOMP] * s;
+ const GLfloat r = (rgba[i][RCOMP] - dest[i][RCOMP]) * tt + dest[i][RCOMP];
+ const GLfloat g = (rgba[i][GCOMP] - dest[i][GCOMP]) * tt + dest[i][GCOMP];
+ const GLfloat b = (rgba[i][BCOMP] - dest[i][BCOMP]) * tt + dest[i][BCOMP];
+ const GLfloat a = (rgba[i][ACOMP] - dest[i][ACOMP]) * tt + dest[i][ACOMP];
#endif
#endif
ASSERT(r <= CHAN_MAX);